Heli Siren

Dr. Heli Siren

Helsingin Yliopisto, Helsinki, Finland

Research Focus & Metrics

Academic Career Length

35Years (1992-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
1 June 2019 in Phytochemistry Reviews
Verified
Journal Article
Open access
PDF file
SMSari Metsämuuronen
Sari Metsämuuronen
HSHeli Siren
Heli Siren
Phenolics and extracted phenolic compounds of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) show antibacterial activity against several bacteria. The majority of phenolic compounds are stilbenes, flavonoids, proanthocyanidins, phenolic acids, and lignans that are biosynthesized in the wood through the phenylpropanoid pathway. In Scots pine (P. sylvestris), the most abundant phenolic and antibacterial compounds are pinosylvin-type stilbenes and flavonol- and dihydroflavonol-type flavonoids, such as kaempferol, quercetin, and taxifolin and their derivatives. In Norway spruce (P. abies) on the other hand, the main stilbene is resveratrol and the major flavonoids are quercetin and myricetin. In general, when the results from the literature regarding the activities of flavonoid glycosides and their aglycones against a total of twenty-one microorganisms are summarized, it was found that phenolic glycosides are less active than the corresponding aglycones, although a number of exceptions are also known. The aglycones in plants respond to various kinds of biotic stress. Synergistic effects between aglycones and their glycosides have been observed. Minimum inhibition concentrations of below 10 mg L−1 against bacteria have been reported for gallic acid, apigenin, and several methylated and acylated flavonols present in these industrially important trees. In general, the phenolic compounds are more active against Gram-positive bacteria, but apigenin is reported to exhibit strong activity against Gram-negative bacteria. The present review lists some of the biosynthesis pathways for the antibacterial phenolic metabolites found in Scots pine (P. sylvestris) and Norway spruce (P. abies). The antimicrobial activity of the compounds is collected and compared to gather information about the most effective secondary metabolites.

6 September 2004 in Ecology Letters
Verified
Journal Article
Closed access
PDF file
IHIlkka Hanski
Ilkka Hanski
CEClaudia Erälahti
Claudia Erälahti
MKMaaria Kankare
Maaria Kankare
OOOtso Ovaskainen
Otso Ovaskainen
HSHeli Siren
Heli Siren

27 August 2007 in Electrophoresis
Verified
Journal Article
Closed access
PDF file
SRStella Rovio
Stella Rovio
JYJari Yli-Kauhaluoma
Jari Yli-Kauhaluoma
HSHeli Siren
Heli Siren

1 December 1997 in Journal of Chromatography A
Verified
Journal Article
Closed access
MRMarja-Liisa Riekkola
Marja-Liisa Riekkola
SWSusanne Wiedmer
Susanne Wiedmer
IVIstván E Valkó
István E Valkó
HSHeli Siren
Heli Siren

1 June 1996 in Journal of Chromatography A
Verified
Journal Article
Closed access
IVIstván E. Valkó
István E. Valkó
HSHeli Siren
Heli Siren
MRMarja-Liisa Riekkola
Marja-Liisa Riekkola

1 November 2020 in Clinica Chimica Acta
Verified
Journal Article
Closed access
HAHenri F. Avela
Henri F. Avela
HSHeli Siren
Heli Siren